Combined heat treatment preparation method in heavy lifting lug preparation process

Abstract

The invention discloses a combined heat treatment preparation method in a heavy lifting lug preparation process, and relates to the technical field of metal heat treatment, the combined heat treatment preparation method comprises quenching and tempering treatment and two times of non-equivalent tempering treatment, the combined heat treatment preparation method comprises the following steps: quenching and tempering treatment: the quenching and tempering treatment procedure is implemented when a lug plate and an arc plate are in a blank stage, high-temperature quenching and tempering treatment are included; the first tempering treatment procedure is arranged after the quenching and tempering treatment procedure, and the lug plate and the arc plate in the first tempering treatment procedure are still blanks; and secondary tempering treatment: the secondary tempering treatment process aims at the object of the heavy lifting lug which is formed by welding when the lug plate and the arc plate are in the constraint state of the clamp, and the welded heavy lifting lug is required to be subjected to tempering treatment along with the clamp. Internal stress is eliminated more thoroughly, and deformation is reduced; the manufacturing precision is improved, the production efficiency is improved, and the process is simple and feasible; and the service life and safety of the lifting lug are improved, and the manufacturing requirements of complex structures are met.

Description

Technical Field

[0001] The invention relates to the technical field of metal heat treatment, and in particular to a combined heat treatment preparation method in the preparation process of a heavy-duty lifting lug. Background Art

[0002] A sling is an anchoring component used to support oil drilling tools. Due to the constraints of the drilling rig's overall structure, the shape and size of the accompanying lifting lugs are limited and cannot be arbitrarily designed. Furthermore, the lifting lugs bear significant loads during drilling tool lifting, placing high demands on lifting safety. To ensure the manufacturing quality of these lifting lugs, the industry generally utilizes thick alloy steel plates welded together. Since alloy steel plates are rolled and formed, their material structure is much denser than castings, naturally possessing higher mechanical strength. Lifting lugs constructed from thick alloy steel plates possess sufficient strength to meet safe lifting requirements.

[0003] In the prior art, patent CN206336922U discloses a lifting lug structure for heavy equipment, which includes a herringbone lifting lug, a top plate and two reinforcing plates. It can disperse the lifting force and withstand a large lifting weight, making the lifting process safer and more efficient. However, the quality of the lifting lug of this steel structure also has defects, namely, internal stress and deformation are generated during welding operations. These two practical problems directly restrict the manufacturing quality of the lifting lug and pose certain safety hazards. Technicians in the machinery manufacturing industry usually use heat treatment processes to reduce the internal stress of steel structural parts. However, in reality, the lifting lugs have a large difference in thickness between the joints between the components, and the absolute value of the internal stress generated during welding is relatively large. The existing single heat treatment method cannot completely eliminate these internal stresses, resulting in a decrease in the matching quality of the lifting lugs and a safety hazard. Obviously, if the internal stress of the lifting lug is not eliminated, the residual internal stress will reduce the matching quality of the lifting lug and may cause safety risks during the lifting process.

[0004] Therefore, the main problem faced by existing technologies in manufacturing heavy lifting lugs is how to completely eliminate the internal stress generated during welding. The existing single heat treatment process cannot effectively solve this problem, resulting in the lug's manufacturing accuracy and safety being affected. Summary of the Invention

[0005] The present invention mainly addresses the problem of incomplete stress elimination in the existing technology when preparing heavy-duty lifting ears. A combined heat treatment preparation method is proposed in the preparation process of heavy-duty lifting ears, which implements multiple heat treatments with different parameters at different preparation stages. The method has a simple combination, is easy to implement, can eliminate internal stress sufficiently and timely, and the quality of the prepared heavy-duty lifting ears is stable.

[0006] In order to solve the above problems, the present invention provides a combined heat treatment preparation method in the preparation process of a heavy-duty lifting lug, which is used to prepare a heavy-duty lifting lug of a steel component with a T-shaped longitudinal cross-section, wherein the steel component includes a vertical lug plate and a horizontal arc plate, and the joint of the lug plate and the arc plate is integrally connected by welding; the combined heat treatment preparation method includes a quenching and tempering treatment and two tempering treatments of unequal values, and the combined heat treatment preparation method includes the following steps: S1. Quenching and tempering treatment: The quenching and tempering treatment is carried out when the ear plate and the arc plate are in the blank stage, and includes high-temperature quenching and tempering treatment; S2. First tempering treatment: The first tempering treatment process is arranged after the quenching and tempering process. At this stage, the ear plate and the arc plate are still blanks; S3. Second tempering treatment: The second tempering treatment process is for the heavy lifting lugs that have been welded and formed while the lug plates and arc plates are constrained by the fixture, and the welded heavy lifting lugs are required to be tempered together with the fixture.

[0007] Preferably, the tempering treatment comprises the following steps: S1-1, high temperature quenching: the quenching furnace heating temperature is 890-910℃, the holding time is 90-100 minutes, and the cooling medium is room temperature water; S1-2. High temperature tempering treatment: The heating temperature of the tempering furnace is 650-670℃, the holding time is 290-310 minutes, and the cooling method is air cooling.

[0008] Preferably, the technical parameters of the first tempering treatment are a tempering furnace heating temperature of 570-590° C., a holding time of 110-130 minutes, and a cooling method of furnace cooling.

[0009] Preferably, the second tempering treatment: the technical parameters of the second tempering treatment are a tempering furnace heating temperature of 395-405°C, a holding time of 110-130 minutes, and a cooling method of furnace cooling.

[0010] Preferably, the clamp includes a base, the arc plate is fitted on the upper end of the base, pressure plates are installed on the upper ends of both sides of the arc plate, and pressure blocks are installed on the upper ends of the pressure plates. Bolts pass through the pressure blocks and the pressure plates in sequence to fix the two sides of the arc plate. Positioning blocks are provided on the side ends of the arc plate and the ear plate where they are welded, and screws pass through the positioning blocks and are fixed to the base.

[0011] Preferably, the upper end of the positioning block is an L-shaped protruding hook, and the lower end of the positioning block is a U-shaped supporting clamp.

[0012] Preferably, the ear plates and arc plates are alloy steel plates of varying thicknesses, forming fillet welds during the welding process. The above-mentioned combined heat treatment method effectively reduces welding stress and deformation, ensuring the manufacturing accuracy and safety of the lifting lugs.

[0013] Preferably, during the preparation of the heavy-duty lifting lug, all heat treatment process steps are carried out without removing the clamp to ensure that the effect of eliminating internal stress is optimal.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: 1. Eliminate internal stress more thoroughly: The present invention implements tempering treatment and two tempering treatments at different temperatures at different stages of the preparation of heavy-duty lifting ears through a combined heat treatment process. It has strong pertinence and can specifically reduce the internal stress generated at different stages and eliminate the internal stress in time. In this way, it not only effectively reduces the welding residual stress, but also eliminates the internal stress to the greatest extent, effectively avoiding the problem of component deformation and structural failure caused by residual stress caused by the single heat treatment process used in the prior art, thereby significantly improving the manufacturing quality and safety of heavy-duty lifting ears.

[0015] 2. Reduced deformation and improved manufacturing precision: During the second tempering treatment after welding, this invention places the lifting lug in a constrained fixture, ensuring that the entire heat treatment process is carried out in a controlled environment. This effectively controls and reduces welding-induced deformation, significantly improving the manufacturing precision of heavy-duty lifting lugs. This effectively addresses the problem of low manufacturing precision often caused by the poor deformation control caused by the inherent large internal stress and corresponding deformation during welding, which is often caused by traditional processes.

[0016] 3. Improved production efficiency and simplified process: The combined heat treatment process of the present invention includes a quenching and tempering treatment followed by two tempering treatments at different temperatures. The process is well-organized, simple to operate, and easy to combine and implement. Compared with existing technologies, the process of the present invention is more streamlined, making it easier to promote and apply in industrial production. The organic combination of multiple heat treatment steps not only reduces equipment requirements but also avoids the increased production costs associated with repeated operations and multiple heat treatments, thereby improving overall production efficiency.

[0017] 4. Enhanced Lifting Eye Service Life and Safety: By implementing multiple targeted heat treatments with varying parameters during the manufacturing process, this invention effectively improves the mechanical properties of heavy-duty lifting eyes, including tensile strength, ductility, and toughness. This multi-step heat treatment eliminates residual stresses in the material during manufacturing and welding, further enhancing the lifting eye's structural stability and durability, ensuring its reliability and safety in high-intensity and high-stress environments.

[0018] 5. Adaptable to the Manufacturing Requirements of Complex Structures: The combined heat treatment process proposed in this invention is particularly suitable for the manufacture of complex structural components such as heavy-duty lifting lugs. Through precise heat treatment process control, it can adapt to the various complex structures and varying material properties encountered during the manufacturing process of lifting lugs, ensuring that the final product meets high-quality and high-precision manufacturing requirements.

[0019] In summary, the present invention solves the problems in the prior art such as difficulty in completely eliminating internal stress, low manufacturing precision, and low production efficiency through an optimized combination of multiple heat treatment processes, and provides an effective combined heat treatment preparation method for high-quality preparation of heavy-duty lifting ears. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the combined heat treatment preparation method in the preparation process of the heavy-duty lifting lug of the present invention.

[0021] Figure 2 This is a schematic diagram of the three-dimensional structure of the heavy-duty lifting eye.

[0022] Figure 3 for Figure 1 Schematic diagram of the three-dimensional structure of the ear plate.

[0023] Figure 4 for Figure 1 Schematic diagram of the three-dimensional structure of the arc plate.

[0024] Figure 5 This is a schematic diagram of the three-dimensional structure of the heavy lifting eye under the constraint of the fixture. DETAILED DESCRIPTION

[0025] The present invention will be further explained below with reference to the accompanying drawings and embodiments.

[0026] Reference Figure 1 As shown, the combined heat treatment preparation method in the heavy-duty lifting lug preparation process includes the following steps: S1, quenching and tempering treatment: the quenching and tempering treatment is carried out when the ear plate 1 and the arc plate 2 are in the blank stage, and includes high temperature quenching and tempering treatment; S2, first tempering treatment: the first tempering treatment process is arranged after the quenching and tempering process, and the ear plate 1 and the arc plate 2 at this stage are still blanks; S3. Second tempering treatment: The second tempering treatment process is for the heavy lifting ears that have been welded and formed while the ear plate 1 and the arc plate 2 are in the restrained state of the fixture, and the welded heavy lifting ears are required to be tempered together with the fixture.

[0027] Reference Figure 2As shown in the figure, the heavy-duty lifting lug is an anchoring component used on oil drilling rigs. Because it bears a large lifting load, it must have sufficient strength to meet the requirements of safe lifting. In addition, the shape and size of the heavy-duty lifting lug are also limited by the structure of the drilling rig. Therefore, the heavy-duty lifting lug in reality is a steel component with a T-shaped longitudinal section, in which the vertical side is the ear plate 1, which is shaped like Figure 3 As shown, the horizontal side is an arc plate 2, shaped like Figure 4 As shown. According to the shape classification, the ear plate 1 and the arc plate 2 are both plate parts, and they are two plates with different thicknesses. When the ear plate 1 and the arc plate 2 are welded, fillet welds are naturally formed on both sides of the joint. A large amount of internal stress will be generated during the welding process, and corresponding deformation will be generated. In order to improve the manufacturing quality of the heavy-duty lifting ear, the present invention proposes a combined heat treatment preparation method, which applies corresponding heat treatment processes at different preparation stages of the heavy-duty lifting ear, in order to achieve the purpose of eliminating more internal stress. The combined heat treatment process includes a tempering treatment process and two tempering treatment processes with different technical parameters. The tempering treatment process is arranged to be implemented when the ear plate 1 and the arc plate 2 are in the blank stage; the first tempering treatment process is arranged after the tempering treatment process, and the ear plate 1 and the arc plate 2 at this stage are still blanks; the second tempering treatment process is aimed at the heavy-duty lifting ear that has been welded under the constraint of the fixture, and the heavy-duty lifting ear is required to be tempered together with the fixture. This situation is shown in the attached figure. Figure 5 The following is a combined heat treatment preparation method in the preparation process of the heavy-duty lifting lug of the present invention.

[0028] The tempering treatment comprises the following steps: S1-1, high temperature quenching: the quenching furnace heating temperature is 890-910℃, the holding time is 90-100 minutes, and the cooling medium is room temperature water; S1-2. High temperature tempering treatment: The heating temperature of the tempering furnace is 650-670℃, the holding time is 290-310 minutes, and the cooling method is air cooling.

[0029] The technical parameters of the first tempering treatment are: a tempering furnace heating temperature of 570-590° C., a holding time of 110-130 minutes, and a cooling method of furnace cooling.

[0030] The technical parameters of the second tempering treatment are: a tempering furnace heating temperature of 395-405° C., a holding time of 110-130 minutes, and a cooling method of furnace cooling.

[0031] This embodiment is a heavy-duty lifting lug with a rated load of 55 tons. Due to its medium specifications and the largest market application, this embodiment is representative. During the preparation of the 55-ton heavy-duty lifting lug, the combined heat treatment process is shown above.

[0032] The combined heat treatment process proposed in the present invention is composed of an organic combination of multiple heat treatment processes, with the first heat treatment process being a tempering treatment. The tempering treatment is a combination of quenching and high-temperature tempering, wherein the quenching process allows the ear plate 1 and the arc plate 2 in the blank to obtain a microstructure mainly composed of fine needle-shaped quenched martensite, and the subsequent high-temperature tempering process obtains a microstructure mainly composed of uniformly tempered sorbite. After the tempering treatment, the mechanical properties of the ear plate 1 and the arc plate 2 in the blank are greatly improved, especially the tensile strength, plasticity and toughness of the material are greatly improved. The ear plate 1 and the arc plate 2 that have been tempered will still generate internal stress in the subsequent preparation process. In order to ensure that the ear plate 1 and the arc plate 2 are accurately positioned and installed in the fixture, the ear plate 1 and the arc plate 2 are subjected to the first tempering treatment before welding.

[0033] The lug plate 1 and the curved plate 2 are then placed together in a fixture and welded together. Because both sides of this butt joint are fillet welds, internal stress and deformation are inevitable during the welding process. The fixture acts as a restraint, limiting its deformation and thus generating internal stress. To address this, the present invention incorporates a second tempering process at this stage, requiring the heavy-duty lifting lug to be placed in the furnace along with the fixture for this second tempering process. This tempering, performed without removing the fixture, completely eliminates the internal stress generated during the heavy-duty lifting lug's production process.

[0034] The clamp is an auxiliary device of the present invention, which consists of a positioning block 4, a base 5, a pressure plate 6 and a pressure block 7. The arc plate 2 is fitted on the upper end of the base 5, and pressure plates 6 are installed on the upper ends of both sides of the arc plate 2. The upper ends of the pressure plates 6 are installed with pressure blocks 7. Bolts 8 pass through the pressure blocks 7 and the pressure plates 6 in sequence to fix the two sides of the arc plate 2. Positioning blocks 4 are provided on the side ends where the arc plate 2 is welded to the ear plate 1, and screws 3 pass through the positioning blocks 4 and are fixed to the base 5. The upper end of the positioning block 4 is an L-shaped protruding hook, and the lower end of the positioning block 4 is a U-shaped supporting clamp. Its combination is as follows Figure 4 As shown, the clamp in the present invention only has the function of determining the welding position and organizing the welding deformation.

[0035] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0036] It should be noted that, in the present invention, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0037] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but is to be construed in the widest manner consistent with the principles and novel features of the invention described herein.

Claims

1. A combined heat treatment preparation method in the preparation process of a heavy-duty lifting lug, used for preparing a heavy-duty lifting lug of a steel member with a T-shaped longitudinal cross section, wherein the steel member comprises a vertical lug plate (1) and a horizontal arc plate (2), wherein the joint of the lug plate (1) and the arc plate (2) is integrally connected by welding; characterized in that: The combined heat treatment preparation method comprises a quenching and tempering treatment and two tempering treatments of unequal values, and the combined heat treatment preparation method comprises the following steps: S1, quenching and tempering treatment: the quenching and tempering treatment process is arranged to be carried out when the ear plate (1) and the arc plate (2) are in the blank stage, and includes high temperature quenching and tempering treatment; S2, first tempering treatment: the first tempering treatment process is arranged after the quenching and tempering treatment process, and the ear plate (1) and the arc plate (2) at this stage are still blanks; S3. Second tempering treatment: The second tempering treatment process is for the heavy lifting ears that have been welded and formed while the ear plate (1) and the arc plate (2) are in the restrained state of the fixture, and the heavy lifting ears connected by welding are required to be tempered together with the fixture.

2. The combined heat treatment preparation method in the heavy-duty lifting lug preparation process according to claim 1, characterized in that: The quenching and tempering treatment comprises the following steps: S1-1, high temperature quenching: the heating temperature of the quenching furnace is 890-910℃, the holding time is 90-100 minutes, and the cooling medium is room temperature water; S1-2. High temperature tempering treatment: The heating temperature of the tempering furnace is 650-670℃, the holding time is 290-310 minutes, and the cooling method is air cooling.

3. The combined heat treatment preparation method according to claim 1 or 2, characterized in that: The technical parameters of the first tempering treatment are as follows: the heating temperature of the tempering furnace is 570-590° C., the holding time is 110-130 minutes, and the cooling method is furnace cooling.

4. The combined heat treatment preparation method according to claim 3, characterized in that: The second tempering treatment: The technical parameters of the second tempering treatment are a tempering furnace heating temperature of 395-405° C., a heat preservation time of 110-130 minutes, and a cooling method of furnace cooling.

5. The combined heat treatment preparation method in the preparation process of heavy-duty lifting lugs according to claim 1 or 2, characterized in that: The clamp comprises a base (5), the arc plate (2) is fitted on the upper end of the base (5), pressure plates (6) are installed on the upper ends of both sides of the arc plate (2), and a pressure block (7) is installed on the upper end of the pressure plate (6). Bolts (8) pass through the pressure block (7) and the pressure plate (6) in sequence, so as to fix the two sides of the arc plate (2). A positioning block (4) is provided at the side end of the arc plate (2) and the ear plate (1) where they are welded, and the screws (3) pass through the positioning block (4) and are fixed to the base (5).

6. The combined heat treatment preparation method in the heavy-duty lifting lug preparation process according to claim 3, characterized in that: The upper end of the positioning block (4) is an L-shaped protruding hook, and the lower end of the positioning block (4) is a U-shaped supporting clamp.

7. The combined heat treatment preparation method according to claim 1, characterized in that: The ear plate (1) and the arc plate (2) are alloy steel plates of different thicknesses, and fillet welds are formed during the welding process.

8. The combined heat treatment preparation method according to claim 1, characterized in that: During the preparation of the heavy-duty lifting lug, all heat treatment process steps are performed without removing the clamp.

Images